Control device for internal combustion engine which operates a throttle corresponding to a controlled variable

Abstract

A delay time is provided in a calculation process until an instructed throttle opening is outputted after a required cylinder inside air filling efficiency is inputted. When calculation timing of a fuel injection quantity comes, an actual cylinder inside air filling efficiency which is achieved in a time ahead by the delay time from the present time is estimated by using an air response model. When a read-ahead time from the present time to closing timing of an intake valve exceeds the delay time, a change amount of the actual cylinder inside air filling efficiency which occurs by the time the read-ahead time elapses from a time point when the delay time elapses is estimated by using an air response model with a deviation between an estimated actual cylinder inside air filling efficiency after the delay time and a target cylinder inside air filling efficiency as a step input value.

The invention claimed is: 
     
       1. A control device for an internal combustion engine which operates a throttle corresponding to a controlled variable, wherein the controlled variable is a cylinder inside air quantity or a physical quantity correlated with the cylinder inside air quantity, the control device comprising:
 an opening command value calculating means which calculates an opening command value to be outputted to the throttle based on a required controlled variable; 
 a delay means which provides a delay time in a calculation process until the opening command value is outputted after the required controlled variable is inputted; 
 an estimating means which estimates an actual controlled variable which is achieved at a predetermined estimated timing; and 
 a fuel injection quantity calculating means which calculates a fuel injection quantity based on the estimated value of the actual controlled variable at the predetermined estimated timing by the estimating means, 
 wherein the estimating means comprises 
 a first estimating means which estimates the actual controlled variable which is achieved after an elapse of the delay time by using a first calculation model defining a response characteristic of the actual controlled variable to the required controlled variable, and 
 a second estimating means which estimates a change amount of the actual controlled variable which occurs by the predetermined estimated timing after a time point at which the delay time elapses, with the actual controlled variable estimated by the first estimating means set as an initial value and the required controlled variable set as a target value, by using a second calculation model defining a response characteristic of the change amount of the actual controlled variable to the difference between the required controlled variable and the actual controlled variable estimated by the first estimation means. 
 
     
     
       2. The control device for an internal combustion engine according to  claim 1 ,
 wherein the first calculation model for use in the first estimating means is a lag element model. 
 
     
     
       3. The control device for an internal combustion engine according to  claim 1 ,
 wherein the second calculation model for use in the second estimating means is a lag element model. 
 
     
     
       4. The control device for an internal combustion engine according to  claim 1 ,
 wherein the predetermined estimated timing is a closing timing of an intake valve. 
 
     
     
       5. The control device for an internal combustion engine according to  claim 4 ,
 wherein the estimation means estimates the actual controlled variable at a time point at which a crank angle reaches a predetermined crank angle which is set before the closing timing of the intake valve, 
 the estimating means determines whether the predetermined estimated timing occurs after the elapse of the delay time based on an engine speed, and 
 the second estimating means estimates the change amount of the actual controlled variable where the predetermined estimated timing is determined to occur after the elapse of the delay time. 
 
     
     
       6. The control device for an internal combustion engine according to  claim 1 ,
 wherein the controlled variable is a filling efficiency of cylinder inside air. 
 
     
     
       7. A control device for an internal combustion engine which operates a throttle corresponding to a controlled variable, wherein the controlled variable is a cylinder inside air quantity or a physical quantity correlated with the cylinder inside air quantity, the control device comprising:
 an opening command value calculating unit which calculates an opening command value to be outputted to the throttle based on a required controlled variable; 
 a delay unit which provides a delay time in a calculation process until the opening command value is outputted after the required controlled variable is inputted; 
 an estimating unit which estimates an actual controlled variable which is achieved at a predetermined estimated timing; and 
 a fuel injection quantity calculating unit which calculates a fuel injection quantity based on the estimated value of the actual controlled variable at the predetermined estimated timing by the estimating unit, 
 wherein the estimating unit comprises 
 a first estimating unit which estimates the actual controlled variable which is achieved after an elapse of the delay time by using a first calculation model defining a response characteristic of the actual controlled variable to the required controlled variable, and 
 a second estimating unit which estimates a change amount of the actual controlled variable which occurs by the predetermined estimated timing after a time point at which the delay time elapses, with the actual controlled variable estimated by the first estimating unit set as an initial value and the required controlled variable set as a target value, by using a second calculation model defining a response characteristic of the change amount of the actual controlled variable to the difference between the required controlled variable and the actual controlled variable estimated by the first estimation unit.